马尾松采伐迹地火烧黑炭对土壤有机碳组分和碳转化酶活性的影响

Effect of Fire-deposited Charcoal on Soil Organic Carbon Pools and Associated Enzyme Activities in a Recently Harvested Pinus massoniana Plantation Subjected to Broadcast Burning

黑炭是不完全燃烧生成的具有高度芳香化结构的含碳颗粒物,能对火烧迹地土壤生态功能产生长期影响.以中亚热带马尾松人工林采伐火烧迹地为研究对象,分析火后黑炭处理[移除(B_(0))、单倍(B_(1))、双倍(B_(2))]、未火烧对照(UB)5 a后土壤有机碳组分[可溶性有机碳(DOC)、微生物量碳(MBC)、易氧化有机碳(ROC)、惰性有机碳(RC)、粗颗粒有机碳(CPOC)、细颗粒有机碳(FPOC)]含量和碳转化酶[葡萄糖苷酶(BG)、过氧化物酶(POD)、多酚氧化酶(POX)、纤维素酶(CBH)、蔗糖酶(SC)]活性特征.结果表明,B_(1)处理土壤DOC、MBC、CPOC、FPOC和RC含量均显著低于UB(P<0.05).B_(2)处理土壤MBC和FPOC含量与UB无显著差异,但显著高于B_(0)处理(P<0.001).B_(1)和B_(2)处理土壤MBC/TC与UB无显著差异,而B_(0)处理土壤MBC/TC显著低于UB(P<0.05).B_(0)、B_(1)和B_(2)处理土壤BG和POD活性显著低于UB(P<0.01).B_(0)和B_(2)处理土壤POX活性显著低于对照(P<0.01).不同黑炭处理土壤TC、DOC、ROC、CPOC和RC含量以及碳转化酶活性无显著差异(P>0.05).冗余分析(RDA)结果显示,SC和POX活性为土壤有机碳组分含量的主要影响因子,其解释率分别为16.3%和12.7%.结果表明,火烧产生的黑炭能加快火后MBC恢复、促进土壤有机碳累积和提高土壤有机碳稳定性,今后在中亚热带人工林经营管理中应重视对黑炭的利用.

Charcoal is a carbonaceous particulate matter with a highly aromatic structure produced by incomplete combustion,and it can cause persistent long-term effects on soil ecological functions.In this study,we determined soil organic carbon pools and associated enzyme activities following five years of different charcoal treatments[charcoal removal(B_(0)),charcoal retained in situ(B_(1)),and the addition of charcoal removed from B_(0)(B_(2))]and the unburnt control(UB)in a recently harvested Pinus massoniana plantation subjected to broadcast burning.The results showed that dissolved organic carbon(DOC),microbial biomass carbon(MBC),coarse and fine particulate organic carbon(CPOC and FPOC),and recalcitrant carbon(RC)contents were significantly lower in B_(1) than those in UB soil(P<0.05).The MBC and FPOC contents of B_(2) soil were comparable to those of UB soil,which were significantly higher than those of B_(0) soil(P<0.001).There was no difference in MBC/TC between the B_(2) and UB soils,whereas MBC/TC was significantly lower in B_(0) than in UB soil(P<0.05).β-glucosidase and peroxidase activities of B_(0),B_(1),and B_(2) soils were significantly lower than that of UB soil(P<0.01),and polyphenol oxidase activity was significantly lower in B_(0) and B_(2) soils than in UB soil(P<0.01).No significant difference in soil TC,DOC,readily oxidized carbon(ROC),CPOC,and RC content as well as associated enzyme activities was observed among the charcoal treatments(P>0.05).Redundancy analysis showed that sucrose and polyphenol oxidase were the key drivers influencing soil organic carbon fractions,accounting for 16.3% and 12.7% of the total variance,respectively.Overall,our findings indicated that fire-deposited charcoal played a positive role in enhancing soil microbial biomass carbon recovery,soil organic carbon accumulation,and stability,highlighting the importance of charcoal in the management of subtropical plantations in the future.